Generally, in order to allow a diode to perform its function within a circuit, electrical connection is established by joining the lead foot of the diode to a terminal plate.
Electrical connection between the diode and the terminal plate is firm in a general use. However, in a terminal plate that is placed within a terminal box for solar cell panel, the terminal plate is used in an environment where the temperature change is considerable, so that the expansion and contraction of the terminal plate in a plane direction of the terminal plate occur frequently. This leads to a problem such that the joining part of the lead foot of the diode to the terminal plate cannot withstand the expansion or contraction and generates cracks, whereby the joining part is easily exfoliated.
In particular, in a terminal box for solar cell panel having a terminal plate that is enlarged for improvement of the effect of dissipating the heat of the diode, such as disclosed in Japanese Patent Application Laid-Open No. 2005-251962, the expansion and contraction of the terminal plate in a plane direction of the terminal plate are greatly transmitted to the joining part that joins the lead foot of the diode to the terminal plate, whereby the aforementioned problem has been conspicuously raised. Therefore, a method has been demanded in which the diode can be allowed to perform its function in a highly reliable state even in such an environment.